1. Field of the Invention
This invention relates to laminated glass structures. This invention particularly relates to laminated glass structures that can withstand severe impact.
2. Description of the Prior Art
Threat-resistant windows and glass structures are known. U.S. Pat. No. 5,960,606 ('606) and U.S. Pat. No. 4,799,376 ('376) each describes laminate windows that are made to withstand severe forces. In International Publication Number WO 98/28515 (IPN '515), for example, a glass laminate is positioned in a rigid channel in which a resilient material adjacent to the glass permits flexing movement between the resilient material and the rigid channel. Other means of holding glazing panels exist such as adhesive tapes, gaskets, putty, and the like can be used to secure panels to a frame.
Prior art windows and glass structures capable of withstanding hurricane-force winds and high force impacts are not trouble-free, however. For example, when subjected to severe hurricane forces the flexing movement in the windows of IPN '515, wherein glass flexes within a rigid channel, gradually pulls the laminate out of the channel resulting in loss of integrity of the structure. In '376, the glass held against the frame can be broken and crushed, causing a loss of structural integrity in the window/frame structure.
In U.S. Pat. No. 6,737,151 B1, incorporated herein by reference, glazing elements that are held in a window frame with the assistance of the interlayer are described. The interlayer provides the means for attachment to the frame. In some circumstances, it can be desirable or even advantageous to use a more flexible material to attach the glazing in the frame. However, flexible thermoplastic materials that have the optical properties suitable for use as an interlayer may not have the modulus or tear strength required for the strenuous applications of threat resistant glazing.